Lethal and sublethal exposure and recovery effects of ozone-produced oxidants on adult white perch ( Morone americana Gmelin)

Abstract

Adult white perch ( Morone americana), acclimated to 15°C, were exposed to a series of ozone-produced oxidant (OPO) concentrations for 96 h using continuous flow bioassay techniques. Toxicity data were analyzed using both response surface modeling and standard probit regression. White perch were also exposed to a series of near and sublethal OPO concentrations, selected from the acute toxicity study, for 96 h and then placed in clean non-ozonated water for 14 days. Blood pH, hematocrit and gill histopathology were analyzed during exposure at 24, 48 and 96 h and after 4 and 14 days in the recovery period. Blood pH and hematocrit levels were analyzed statistically using standard ANOVA and multiple range tests. Histopathological effects were examined using both light microscopy and scanning electron microscopy. The 24-, 48- and 96-h LC 30's were 0.38, 0.26 and 0.20 mg OPO l −1, respectively. Blood pH was significantly reduced at concentrations ⩾0.15 mg OPO l −1 but not at 0.10 mg l −1 or lower concentrations. Hematocrit significantly increased at concentrations ⩾0.10 mg OPO l −1. Histopathological examination revealed minimal effects on gill tissue at 0.01 mg OPO l −1, moderate epithelial sloughing and heavy mucus production at 0.05 mg OPO l −1 and extreme tissue damage at concentrations ⩾0.10 mg l −1. Results from both the acute toxicity and the exposure and recovery study were compared with the effects of chlorine-produced oxidants (CPO) obtained from the literature. Both OPO and CPO appear to have similar effects on adult white perch.